Presentations
 
1.
Arka Banerjee, KIPAC/Stanford University
Signatures of Self-Interacting dark matter on stacked cluster density profiles and subhalo distributions

August 6, 2019 (4:00 PM - 4:15 PM)

PDF, 4.35 MB
Co-authors: Susmita Adhikari, Neal Dalal, Surhud More, Andrey Kravtsov
Non-gravitational interactions between dark matter particles with strong scattering, but relatively small annihilation and dissipation, has been proposed to match various observables on cluster and group scales. In this paper, we present the results from large cosmological simulations which include the effects of different self-interaction scenarios. In particular we explore a model with the differential cross section that can depend on both the relative velocity of the interacting particles and the angle of scattering. We focus on how quantities, such as the stacked density profiles, subhalo counts and the splashback radius change as a function of different forms of self-interaction. We find that self-interactions not only affect the central region of the cluster, the effect well known from previous studies, but also significantly alter the distribution of subhalos and the density of particles out to the splashback radius. Our results suggest that current weak lensing data already puts constraints on the self-interaction cross-section that are only slightly weaker than the Bullet Cluster constraints ($sigma/m lesssim 2$ cm$^2/$g), and future lensing surveys are going to tighten them even further making halo profiles on cluster scales a competitive probe for DM physics.
2.
Simon Birrer, UCLA
Strong lensing probes of dark matter

August 5, 2019 (3:30 PM - 4:00 PM)

PDF, 19.64 MB
overview talk. I will describing the phenomena of strong gravitational lensing and review different observational methods and analysis techniques ranging from micro-lensing of stars, milli-lensing of galaxies, unresolved quasar flux ratios to galaxy clusters. I will then discuss the prospects of strong lensing in quantifying dark matter in the next decade and highlight the role of LSST in combination with other ground and space based facilities.
3.
Jonathan Blazek, EPFL
Dark matter and large-scale structure

August 5, 2019 (2:00 PM - 2:30 PM)

PDF, 36.16 MB
TBD
4.
Kimberly Boddy, Johns Hopkins University
Tidal stripping of SIDM halos

August 7, 2019 (9:30 AM - 9:45 AM)

PDF, 10.72 MB
5.
Alyson Brooks, Rutgers
Understanding Dwarf Galaxies in order to Understand Dark Matter

August 5, 2019 (12:00 PM - 12:30 PM)

PDF, 11.48 MB
In just a few short years the Large Synoptic Survey Telescope will begin survey operations, leading to the discovery of hundreds of Local Group dwarf galaxies, including hundreds of dwarf galaxies in the ultra-faint regime. These tiny galaxies provide a test of both our understanding of dark matter and of star formation. But are we ready for these discoveries? Will be able to easily interpret the information that they hold? In this talk, I will highlight uncertainties in our theoretical modeling of both dark matter and baryonic physics that will complicate our interpretation of even pure dwarf galaxy number counts. I will also discuss potential paths forward, and the clues that dwarfs may provide about their physical conditions in the early Universe.
6.
Chihway Chang, KICP
Weak lensing as a tool for dark matter physics

August 5, 2019 (2:30 PM - 3:00 PM)

PDF, 77.08 MB
Weak lensing is one of the main science drivers for LSST — we expect to measure the slightest distortion of billions of galaxies from dark matter distributed in the cosmos. Most of the focus for developing weak lensing analyses have been focusing on probing large-scale structure and constraining cosmology. However, in this talk I overview a collection of topics where weak lensing can also provide additional handles for studying the nature of dark matter, in addition to the more traditional approaches.
7.
Francis-Yan Cyr-Racine, University of New Mexico
Particle Dark Matter: The Discovery Potential of Milky Way Satellites in the LSST Era

August 5, 2019 (1:30 PM - 2:00 PM)

PDF, 23.06 MB
Co-authors: Ethan Nadler, Manoj Kaplinghat, Alex Drlica-Wagner, and others.
The abundance of small dark matter subhalos around the Milky Way depends, in part, on the properties of dark matter in the early Universe. For instance, free-streaming or interactions with a relativistic species could erase small-scale fluctuations at early time and lead to a dearth of low-mass subhalos around our galaxy. In this work, we present a simplified yet realistic model for how these small subhalos are populated by faint galaxies, taking into account how the dark matter microphysics affects the central densities and abundance of these objects. Using this approach, we determine the constraining power of current observations, phrasing our constraints in terms of the suppression scale in the matter power spectrum and the dark matter self-interaction cross section. We also perform forecasts for how much LSST, when combined with kinematic measurements from 30-meter class telescopes, could improve these constraints.
8.
William Dawson, Lawrence Livermore National Lab
Black Holes Hiding in Plane Sight

August 5, 2019 (4:00 PM - 4:30 PM)

PDF, 18.45 MB
Co-authors: Nathan Golovich, Jessica Lu, Casey Lam, and the PALS Collaboration.
Despite numerous indirect constraints on the abundance of black holes in the universe there remains tension in the field as to the robustness of these constraints, with limits from the same probe often moving by as much as several orders of magnitude depending on the analysis. Gravitational microlensing of black holes in the Milky Way and local volume offers the promise of a more direct census of black holes. However, this technique has traditionally been hampered by the lens mass-distance degeneracy, where for a given photometric microlensing event could be due to a low or high mass lens depending on its distance from the observer and source star. While this degeneracy can be broken with the combination of photometric and astrometric microlensing measurements, the astrometric measurements are resource intensive. We will introduce a means of detecting black holes via photometric microlensing alone and present candidate black holes detected with this method.
9.
Adrienne L Erickcek, UNC Chapel Hill
Probing the early Universe with dark matter

August 6, 2019 (11:45 AM - 12:00 PM)

PDF, 12.57 MB
10.
Chris Fassnacht, UC Davis
New constraints on dark matter from gravitational lensing

August 6, 2019 (2:00 PM - 2:15 PM)

PDF, 8.31 MB
Co-authors: Jen-Wei Hsueh and the SHARP collaboration.
I will present results from a new analysis of the radio and mid-IR flux ratios in a small sample of strong gravitational lens systems. This analysis updates the one used in the classic Dalal and Kochanek paper in three important ways: (1) Includes complex baryonic components in the lensing galaxy when warranted by high resolution imaging, (2) includes line of sight halos, and (3) considers WDM models. Our limits on the thermal relic mass in a WDM model are comparable in constraining power with those from Ly-alpha analyses.
11.
Maurizio Giannotti, Barry University
Astrophysics of axions and axion like particles

August 6, 2019 (11:15 AM - 11:30 AM)

PDF, 2.8 MB
I will review the constraints and hints on axions from astrophysical observations and discuss the role LSST will play in improving our understandings in this field.
12.
Daniel Gilman, University of California, Los Angeles
Constraining models of warm and self-interacting dark matter with quadruple-image strong gravitational lenses

August 6, 2019 (1:45 PM - 2:00 PM)

PDF, 13.66 MB
Co-authors: Simon Birrer
Tommaso Treu
Anna Nierenberg
Andrew Benson
Omid Sameie

Strong gravitational lensing offers a direct probe of dark matter structure on sub-galactic scales. Two models in particular, warm and self-interacting dark matter (WDM and SIDM, respectively), make unique predictions regarding the abundance and structure of dark matter halos below 10^8 solar masses. The former is characterized by a dearth of structure below a free-streaming scale that depends on the formation mechanism and mass of the dark matter particle, while scattering between dark matter particles in SIDM results in cored density profiles in individual halos. I will describe how, through a forward modeling approach in which we account for halos both in the main lens plane and along the line of sight, we can constrain the physics relevant to both of these dark matter models. Specifically, in the case of WDM we can achieve constraints on the mass of thermal relic of dark matter particles of ~3 keV with the current sample size of quadruple-image strong lenses (quads), independent of other constraints such as those from the Lyman-alpha forest. In the era of LSST, which will increase the sample size of quads by orders of magnitude, these bounds will improve significantly, ruling out WDM particles free-streaming lengths equivalent to that of a 6 keV thermal relic. This will conclusively rule out or uphold WDM models sometimes invoked as resolutions to the the so-called ‘Small Scale Crisis’ of CDM, and will test a fundamental prediction of CDM on sub-galactic scales.
13.
Vera Gluscevic, USC
Cosmological Probes of Dark Matter Physics

August 5, 2019 (11:30 AM - 12:00 PM)

PDF, 4.42 MB
14.
David Hendel, University of Toronto
Stellar streams and Milky Way substructure in the era of LSST

August 7, 2019 (10:45 AM - 11:00 AM)

PDF, 2.95 MB
Stellar tidal streams from disrupting globular clusters are among the most dynamically cold systems known. This makes them sensitive to both the global structure of the Milky Way's gravitational potential and to substructures within it. In particular, a passing dark matter subhalo can cause a gap to form in the stream - even if the subhalo is small enough to contain no stars or gas of its own and therefore be otherwise invisible. Detection of these disturbances is a promising way to constrain the subhalo mass function. I will describe ongoing work to forecast LSST's ability to identify and characterize stream gaps and compare its expected performance with those of other current and future surveys; it ranks among the most effective due to its depth, photometric precision, and sky coverage.
15.
Marc Kamionkowski, Johns Hopkins University
Black holes, baryons, axions, the Sagittarius dwarf galaxy, and dark matter

August 5, 2019 (10:00 AM - 10:30 AM)

PDF, 15.76 MB
16.
Rocky W Kolb, University of Chicago
Dark Matter Landscape

August 5, 2019 (9:30 AM - 10:00 AM)

PDF, 14.91 MB
17.
Alexie Leauthaud, UCSC
Weak lensing Measurements of the Dark Matter Halose for dwarf galaxies

August 6, 2019 (4:15 PM - 4:30 PM)

PDF, 5.91 MB
Co-authors: Singh, Sukhdeep; Luo, Yifei; Ardila, Felipe; Greco, Johnny P.; Capak, Peter; Greene, Jenny E.; Mayer, Lucio
I will present forecasts for the expected signal-to-noise of galaxy-galaxy lensing measurements for dwarf galaxies with upcoming surveys such at HSC, LSST, Euclid, and WFIRST.
18.
Ting Li, Fermilab / Carnegie Observatories
Dark Matter Science with Spectroscopy

August 7, 2019 (11:15 AM - 11:30 AM)

PDF, 5.24 MB
I will discuss the dark matter science cases that requires spectroscopic capibility such as DESI, MSE, etc.
19.
Jennifer Marshall, Texas A&M University
The future of massively multiplexed spectroscopy: the Maunakea Spectroscopic Explorer

August 5, 2019 (4:30 PM - 5:00 PM)

PDF, 3.3 MB
Numerous international astronomy reports have recently highlighted the need for fully dedicated, large aperture, massively multiplexed spectroscopy in the optical and near-Infrared wavelength regimes. Such a facility is the most obvious missing link in the emerging network of ground-based observational facilities world-wide. The Maunakea Spectroscopic Explorer (MSE) is a planned 11-m telescope facility designed to fill this scientific gap. MSE is completely dedicated to multi-object optical and near-Infrared spectroscopy surveys of millions of astrophysical objects at a range of spectral resolutions. In this talk I will review the current design status of the project, provide an overview of MSE's scientific scientific capabilities, and highlight its capacity to study dark matter.
20.
Sam McDermott, FNAL
Stellar Constraints on Dark Matter and Dark Sectors

August 5, 2019 (11:00 AM - 11:30 AM)

PDF, 8.71 MB
21.
Siddharth Mishra-Sharma, New York University
Analyzing a population of galaxy-galaxy strong lenses to infer substructure properties using likelihood-free inference

August 6, 2019 (2:15 PM - 2:30 PM)

PDF, 10.79 MB
Co-authors: Johann Brehmer and Kyle Cranmer
I will describe novel methods to infer population properties of dark matter substructure contained in strongly lensed galaxies, such as its overall abundance and shape of the subhalo mass function, using likelihood-free (or simulation-based) techniques. These methods use calibrated outputs of neural networks as surrogates for the likelihood ratio, and provide a fast and principled way to analyze an ensemble of strong lensing images in order to infer substructure population properties with the overall aim of revealing the underlying dark matter particle physics.
22.
Ethan O Nadler, KIPAC/Stanford
Milky Way Satellites: Probes of Dark Matter Microphysics

August 7, 2019 (9:00 AM - 9:15 AM)

PDF, 15.46 MB
Co-authors: Vera Gluscevic, Kim Boddy, Risa Wechsler
As luminous tracers of the smallest observationally accessible dark matter halos, faint satellite galaxies orbiting the Milky Way have the potential to dramatically improve our understanding of dark matter microphysics. However, the confounding effects of baryonic physics on halo abundances and galaxy formation have made the interpretation of the observed MW satellite population unclear. I will describe a forward model for the MW satellite population based on high-resolution zoom-in simulations that marginalizes over these astrophysical effects and accounts for the relevant numerical and observational uncertainties. This method yields limits that are competitive with current constraints on warm and/or interacting dark matter models, including sterile neutrinos, ultra-light axions, and self-interacting dark matter. I will discuss limits on DM-baryon scattering in WIMP-like models that improve upon CMB and Lyman-alpha forest analyses by several orders of magnitude.
23.
Annika Peter, OSU
Setting the Stage

August 5, 2019 (9:00 AM - 9:30 AM)

PDF, 17.12 MB
24.
Troy J Raen, University of Pittsburgh
Dark Matter in Stars

August 6, 2019 (11:30 AM - 11:45 AM)

PDF, 8.7 MB
Co-authors: Héctor Martínez-Rodríguez,
Andrew R. Zentner,
Travis J. Hurst,
Carles Badenes,
Rachel Tao

Our work explores the effects of energy transport by spin-dependent Asymmetric Dark Matter (ADM) in stars of mass $0.8 leq mathrm{M}_{star}/mathrm{M}_{odot} leq 5.0$ using the publicly available code Modules for Experiments in Stellar Astrophysics ( exttt{MESA}). If dark matter (DM) can scatter with standard model particles, it can be captured by stars orbiting in DM halos and contribute to stellar energy transport via continued scattering. Despite ongoing terrestrial direct detection experiments, DM has not been observed and the available parameter space for classic WIMPs (Weakly-Interacting Massive Particles) is shrinking rapidly, prompting research into other models. ADM predicts a DM particle that is less massive than typical WIMPs and does not self-annihilate - a scenario that allows a star to build up a large quantity of DM with orbital paths crossing distinct regions of the star. Thus, the energy transported by DM can alter the stellar evolution. Our results show that, while the details vary as a function of stellar mass, the net effect on stars in rich DM environments is a significant, and potentially observable, decrease in stellar lifetimes. In this talk, I discuss the specific effects of DM energy transport on exttt{MESA} models and present results in the form of isochrones that may be used in the future to constrain DM properties by comparison with observed star clusters.
25.
Alexander Riley, Texas A&M University
The velocity anisotropy of the Milky Way satellite system

August 7, 2019 (9:15 AM - 9:30 AM)

PDF, 27.77 MB
I will discuss the orbital kinematics of the Milky Way satellite system utilizing the latest systemic proper motions for 38 satellites based on data from Gaia DR2. Combining these data with distance and line-of-sight velocity measurements from the literature, I model the velocity anisotropy as a function of Galactocentric distance and compare the MW satellite system with those of simulated MW-mass halos from the APOSTLE and Auriga simulation suites. The anisotropy profile for the MW satellites increases with distance, where satellites closer to the Galactic centre have tangentially-biased motions and those farther out have radially-biased motions. Comparison with the simulations suggests this shape of the anisotropy profile may be attributed to the central stellar disk preferentially destroying satellites on radial orbits, or intrinsic processes from the formation of the Milky Way system.
26.
Victor H Robles, University of California Irvine
Using Simulations to constrain the nature Dark Matter in the era of new telescopes

August 6, 2019 (3:30 PM - 3:45 PM)

PDF, 25.34 MB
27.
Neelima Sehgal, Stony Brook University
CMB-HD: Probing Dark Matter Particle Properties with Ultra-High-Resolution CMB Lensing

August 6, 2019 (4:30 PM - 4:45 PM)

PDF, 6.22 MB
I will discuss a novel and powerful way to probe dark matter particle properties using deep, high-resolution cosmic microwave background (CMB) gravitational lensing measurements. These measurements can distinguish between cold dark matter and alternative dark matter models that can explain observational puzzles of small-scale structure. I will also discuss a new experiment being developed, called CMB-HD, that can achieve this science and also open new windows on the early Universe, gas and galaxy evolution, planetary studies, and the transient sky.
28.
Nora Shipp, University of Chicago
Stellar streams with DES and Gaia

August 7, 2019 (11:00 AM - 11:15 AM)

PDF, 1.91 MB
TBD
29.
Kyriakos Vattis, Brown University
Dark matter decaying in the late Universe can relieve the H0 tension

August 6, 2019 (11:00 AM - 11:15 AM)

PDF, 4.54 MB
I will discuss the cosmological effects of two-body dark matter decays in which the products of the decay include a massless and a massive particle. In our recent analysis, we show that if the massive daughter particle is slightly warm, such a model can help relieve the tension between distance ladder measurements of the present-day Hubble parameter with measurements from the cosmic microwave background.
30.
Mei-Yu Wang, Carnegie Mellon University
Probing Dark Matter Particle Properties with dark matter phase space information in the Milky Way satellites

August 7, 2019 (9:45 AM - 10:00 AM)

PDF, 3.55 MB
Co-authors: Alex Drlica-Wagner, Ting Li, Louis Strigari, Kimberly Boddy, Jason Kumar
Milky Way satellite galaxies are compelling targets for dark matter searches due to their proximity, high dark matter content, and low astrophysical backgrounds. Detailed studies of the stellar kinematics of satellite galaxies provide information on their dark matter content and velocity distribution. In this talk, I will discuss how we can quantify the expected stellar kinematic measurement precision for Milky Way dwarf galaxies using mock stellar kinematic data and assess the capability of current and future spectroscopic instruments by performing mock observations. I will discuss how those measurement precisions can impact on several dark matter model constraints such as dark matter annihilation/decay cross section limits for both velocity-independent and velocity-dependent models from indirect detection experiments.
31.
Lukasz Wyrzykowski, Warsaw University Astronomical Observatory, Poland
Dark Matter and Black Holes from microlensing in OGLE, Gaia and LSST

August 6, 2019 (1:30 PM - 1:45 PM)

PDF, 6.66 MB
Co-authors: K.A.Rybicki
K.Kruszynska

As shown by gravitational wave detections, galaxies harbour an unknown population of black holes at high masses of either stellar or primordial origin. In our Galaxy such dark objects can be found and studied solely via gravitational microlensing method. We describe our search for dark matter in form of compact objects in both archival OGLE data and among on-going microlensing events found by OGLE and Gaia. We show how a combination of time-domain astrometry and photometry will allow to uniquely derive masses and distances, and hence to recognise these dark lenses. Even sparse sampling of the Galactic Disk by the LSST should allow us to discover hundreds of events caused by black holes and, for the first time, to describe the demographics of the unseen component of the Milky Way.